Design,Synthesis And Flame Retardant Application Of Zeolite-and Phytic Acidmetal Organic Framework Materials

Recently,metal organic framework materials?MOFs?have been used in the field of flame retardancy due to their rich designability?providing metal elements,flame retardant elements?N,P,etc.?or groups?.However,the flame-retardant efficiency of MOFs is low due to its organic components.At present,the synergetic method has been used to improve flame-retardant efficiency of flame retardant.At the same time,the multifunctional composites with excellent comprehensive properties?including flame retardant properties,mechanical properties,etc.?have been widely valued.Based on the mechanism of flame retardants and flame retardant systems,a variety of highly effective and multifunctional MOFs flame retardants were synthesized from molecular design.This paper is mainly divided into two parts:?1?the design and synthesis of zeolites based metal organic framework?ZIF-8?encapsulation and hybrid materials,and its application in epoxy resin?EP?;?2?on the basis of the synthesis and application of phytic acid based MOFs,a layer by layer assembly method was used to combine phytic acid based MOFs with traditional flame retardant magnesium hydroxide to expand its functionality and further been applied to multi-functional polymer materials.The specific research work of this paper is as follows:?1?Based on the small window and large pore effect of ZIF-8,two novel ZIF-8encapsulation flame retardants,including ZIF-8 encapsulated hexachlorocyclotriphosphazene?ZIF-8@HCCP?and ZIF-8 encapsulated ferric acetylacetonate?ZIF-8@Fe?acac?₃?,was prepared by one-step solution synthesis method.The encapsulation materials have a dodecahedron structure.And the initial decomposition temperature of the encapsulation materials?that of ZIF-8@HCCP is above 550?,and that of ZIF-8@Fe?acac?₃ is above 570??is higher than that of the package?that of HCCP is 106?,and that of Fe?acac?₃ is 208??.The encapsulation materials show high efficiency in flame retardant and smoke suppression for EP.Compared with pure EP,the peak of heat release rate?PHRR?value,the peak of smoke release rate?PSPR?and CO production rate of EP/ZIF-8@HCCP?4 phr,the encapsulation quantity is 9.92%?were decreased by 56.2%,57.2%and 45.7%,respectively.Compared with pure EP,the PHRR,PSPR and total smoke production?TSP?of EP/ZIF-8@Fe?acac?₃?4 phr,the encapsulation quantity is 10.73%?decreased by 37.9%,30.8%and 19.5%,respectively.The flame-retardant mechanism was concluded with“quenching mechanism”obtained by the analysis of thermogravimetric analyzer coupled with fourier transform infrared spectrometer and char residue.The“quenching mechanism”is that the structure of ZIF-8 collapses with the rapid release of encapsulation materials?HCCP,Fe?acac?₃?,showing instantaneous gas-phase and condensed-phase flame-retardant behavior.In addition,ZIF-8@HCCP and ZIF-8@Fe?acac?₃ can edow EP with good mechanical properties.?2?Considering the synergistic flame retardancy of P,N,S and Zn,a ZIF-8/poly?cyclotriphosphazene dihydroxydiphenylsulfone??ZIF-8/PZS?with core-shell and dodecahedron structure was successfully synthesized by a two-step solution method.X-ray diffraction?XRD?,Fourier transform infrared spectroscopy?FTIR?,scanning electron microscopy?SEM?and thermogravimetric analysis?TGA?were used to characterize the crystalline phases,surface functional groups,morphology and thermal stability of the hybrid.When added to EP,ZIF-8/PZS can edow EP with excellent flame retardant and smoke suppression properties.4 phr ZIF-8/PZS can catalyzes the early degradation of EP to form more stable,continuous and dense char layers,which reduced the PHRR,PSPR and TSP values of EP by 29%,26%and 10%,respectively.MOFs?m-pmofs?M=Zn,Sn,Cu??were synthesized by one-step solution method.The synthesis method of m-pmofs is simple and rapid,and amorphous hybrid flame retardant is finally obtained.The initial decomposition temperature of m-pmofs was above 160°C and had good dispersion in EP.4 phr m-pmofs?M=Zn,Sn,Cu?composites have excellent flame retardant and smoke suppression properties,and the corresponding phrr values of EP composites are reduced by 32.1%,50.2%and 44.0%,respectively.This is the result of the catalytic carbonization of phosphate and oxide formed by Zn pmofs and Cu pmofs and phosphoric acid and Sn O 2 formed during combustion of Sn pmofs in condensed phase.?3?Phytic acid-based MOFs?M-PMOFs?M=Zn,Sn,Cu??were successfully synthesized by one-step solution method.The synthesis method of M-PMOFs is simple and rapid,and amorphous hybrid flame retardant is finally obtained.M-PMOFs is a kind of reticulated mesoporous material with small particles with its initial decomposition temperature above 160?.The dispersion of M-PMOFs in EP is good.EP composite with 4phr M-PMOFs?M=Zn,Sn,Cu?exhibited excellent flame retardant and smoke suppression propertie.Compared with pure EP,the PHRR values decreased by 32.1%,50.2%and 44.0%,respectively.This is the result of the catalytic carbonization of phosphate and oxide?formed by Zn-PMOFs and Cu-PMOFs in combustion?and phosphoric acid and Sn O₂?formed during combustion of Sn-PMOFs?in condensed phase.?4?On the basis of Sn-PMOFs in the previous part,a magnesium hydroxide@Sn-PMOFs@zinc tannate?MH@PASn@TAZn?with core-shell structure was successfully synthesized by layer by layer assembly strategy and was used to improve the flame retardancy,smoke suppression and mechanical properties of flexible polyvinyl chloride?PVC?.The LOI value of the PVC/MH@PASn@TAZn?10 phr?composite was 30.3%,which was higher than that of pure PVC?24.9%?.PASn and TAZn can synergistically catalyze the formation of continuous high-density carbon residue in PVC combustion process.At the same time,MH releases water vapor,which plays a dilution effect in the gas phase.These effects reduced the PHRR,PSPR and TSP values of PVC composite by 42.3%,31.1%and 35.2%,respectively.In addition,PASn and TAZn enhanced the interfacial compatibility between MH@PASn@TAZn and PVC,resulting in significant improvement on tensile strength,elongation at break and impact strength of PVC/MH@PASn@TAZn.